Metallic and polymer bone plates have been used to immobilize bone segments to allow healing. These plates are typically affixed to the outer surface of the bone segments, while putting the segments in close enough proximity or contact to permit bone regrowth between the segments. One deficiency of a surface mounted plate is that it can create soft tissue irritation and impingement.
An alternative mechanism for fixing bone segments is also known wherein a mechanical device is placed within the bone segments. This type of system is commonly referred to as an intramedullary nail or rod. One of the first uses of such a rod occurred in 1939 by Gerhard Küntscher. To date, two limitations have prevented intramedullary (“IM”) nails from being used more frequently. First, installing a nail that is long enough to span a gap between bone segments while providing sufficient length to attach to the bone segments typically requires insertion of the IM at the most distal or proximal ends of the bone.
For example, referring now to FIGS. 1A-1C, there is shown a bone 10 having a fracture 10a disposed between its proximal end “P” and distal end “D”. In order to use the IM nail 20 of the prior art, the IM nail 20 is first inserted into the intramedullary cavity C of the bone 10, through its proximal end “P”, and pushed through the intramedullary cavity in the direction of arrow “A”. Once the IM nail 20 is seated in a desired position in the intramedullary cavity C (i.e., a position spanning a portion of the proximal segment of the bone, the fracture itself, and a portion of the distal segment of the bone 10), the proximal portion of the IM nail 20 is fixed to the proximal segment of the bone 10 using the locking screws 25, as shown more particularly in FIG. 1B.
Referring now to FIG. 1C, once the IM nail 20 has been fixed at the proximal end to proximal bone segment, the distal bone segment is moved in the direction of the arrow B until the fracture 10a is reduced. At this time, holes can be drilled through the distal segment of the bone 10 and the distal end of the IM nail 20 is secured to the distal segment of the bone using the locking screws 27.
A second limitation to the use of known IM nails is that it can be very difficult to adjust either the length of the IM nail (to bring the bone segments into the proper position/alignment), or to rotationally and/or angularly adjust the bone segments prior to reduction of the fracture.
Although the use of known IM nails can reduce soft tissue irritation and be less traumatic to the patient than a plate (i.e., by requiring less surgical exposure and stripping of the periosteum during implantation), they still suffer the above-discussed shortcomings.
What is needed is a device that reduces or eliminates the difficulties experienced when using known IM nails. What is further needed is a device that can provide greater adjustability and improved surgical insertion options to benefit patients with fractures or osteotomies.